Sunday, June 24, 2018

Milling Stand and Ball Turning Attachment

I had a brief moment to work on some "projects", so I took that and ran with it.  First up was a ball turning attachment for the lathe.  I picked up some 5" x 12" x 5/8" steel plate, and drew up the fork on it.  Then I drilled a few holes to make turning corners in the bandsaw a little easier :

Once that was complete, I drilled along the swing arm on the inside (the blade wouldn't be able to make that turn, even with a drilled hole), and then cut along the lines.  I simply used a hammer to break out the inside chunk since I drilled along the base line of it.  Before freeing the entire pieces, I drilled sideways (which will become vertical when complete) to ensure that the pivot points are lined up.  You will see that in the second picture :

Then, the final cut along the hilt where it will sit in the tool post holder to free it all up.  Here is an exploded view of where everything ended up in the plate steel :

The "forks" were still a little rough :

At that point, I used a flap disc on the angle grinder and the milling machine to clean things up.  My biggest worry was making sure the drilled holes when expanded remained on the same axis.  If the top axis was even slightly not lined up with the bottom axis, it won't pivot very easily.  This meant that I MUST drill the final holes in line with the other end.  A drill press won't cut it because it wouldn't guarantee that the axis' would be parallel.  So, I used the live center to keep the points lined up, and a drill bit in a collet.  This allowed me to swap sides, and drill them out.  I did both the frame and the c-channel that pivots.  The large channel was drilled with 3/8" (0.375"), and the c-channel was drilled with a 1/4" (0.250").  On the c-channel, because it was smaller than the swing, I had to use a board between the ways to keep it solid.

Once done, I verified that I could put a 3/8" rod through the holes (meaning they were parallel).  Perfect!

I then had to cut some bushings.  They were first turned down (with a flange) to a minor outside diameter of 0.375" to match the holes.  I drilled them to 0.250" to match the sizes of holes in the c-channel holes.

I pressed the bushings into the frame.

Then, to make sure the whole thing would work properly, I grabbed a 0.250" (1/4") rod and placed it through all of the holes, and ensured that everything turned properly.

The next steps are to broach the tool holder in the c-channel/swing arm (you can see it in the picture above) into a square hole, cut some flats on the 0.250" rod and install some set screws for the rods and tools.  After that, a simple handle and we're good to go!

Notice the square broach.  I built a broach out of 7mm HSS.  Being a stupid idiot, I first tried turning it on a lathe.  That is a bad idea - it will break your carbide tooling, and does nothing to the square.  Next, I used a grinder to make it "round" and cut "reliefs" in it.  This did nothing more than get it jammed into the round hole.  So, I used files to make the hole a little more square, then fed a 6mm HSS blank through it (squared up the hole to 6mm, still less than the 1/4" I wanted for tooling).  So, I then fed the 7mm "rounded" broach.  I was puckered up a little, but I ended up with a square hole.  I then locked it onto my mill, cut a flat, and then drilled a hole for a set screw.  Another note, I didn't see many options for a #12 set screw, so I had to go up to a 1/4" set screw.

After tapping that, I took all thread, and put a bend in it using heat and a press, then put it all together.  All I need now is an XL tool holder for the AXA, and I can tell everyone I have balls of steel!

Speaking of the milling machine, I also built a stand, since it is heavy and I don't like moving it around.  I also have limited space on tool storage, so I had to make it "mobile".  Turned out okay :

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